SEA CREATURES OF OUR ATLANTIC SHORES
BY ROY WALDO MINER*
AUTHOR OF "CORAL CASTLE BUILDERS OF TROPIC SEAS,"
IN THE NATIONAL GEOGRAPHIC MAGAZINE
A WE STAND on the seashore at the
full of the tide and look out over
the swelling floods surging in from
the distant horizon, our feet are on the
threshold of an enormous empire, so vast in
extent and population that the achieve
ments of the haughtiest rulers of mankind
are dwarfed by comparison.
Though fleets sail over its depths, they
make no significant impression upon this
immense realm.
FROM THE SEA CAME ALL LIFE
The subjects of this empire swarm
through the waters in myriads totaling far
greater numbers than all the life of the
continental world. In fact, scientific in
vestigations indicate that the oceans were
the original abode of life on the globe, and
that the continents were peopled from that
inexhaustible reservoir.
Geologists believe that the depressions
now occupied by the oceans always have
been located in approximately their present
positions during the entire history of the
earth, and that the foundations of the land
masses likewise have been situated nearly
as they are at the present time.
But during the great geological periods,
the ocean has repeatedly invaded their
edges and even their interior basins, some
times to an enormous extent, forming shal
low epicontinental seas.
Thus, all the continents of the world are
bordered by a strip of shallow sea, the con
tinental shelf, which slopes gradually from
the coast to depths varying from 100 to
1,000 fathoms at its outer edge. Beyond
this limit there is usually a more rapid
gradient to the main floor of the ocean
the continental slope.
This world-wide shallow strip is of major
importance to the life of the seas.
The present article deals especially with
the mollusks and other small creatures in
habiting the continental shelf which borders
the Atlantic coast of North America from
Nova Scotia to New York, and includes the
extensive New England fisheries.
Ina
later article a contrast will be drawn be
tween this life of northern waters and that
* Curator of Marine Life, American Museum of
Natural History.
of the warmer seas of the southern Atlantic
coast.
A most remarkable stretch of shore this
is. Its southern half is of comparatively
even contour, but, beginning with the region
of Cape Hatteras, the coast to the north
ward has subsided and is indented with deep
bays and irregularities, finally terminating
in the long curving and tapering indenta
tion of the Gulf of Maine.
The latter is the most noteworthy fea
ture of the coast, its wide mouth being
guarded on either hand by Cape Cod and
Cape Sable, and its inner reaches narrow
ing to a double apex in the Bay of Fundy
(map, page 212).
All this northern half of the Atlantic sea
board is a succession of drowned valleys,
and its topography and geological history
indicate that it has subsided beneath the
waves of the sea during relatively recent
times. On the other hand, the even out
line of the coast from Hatteras south to
Florida shows no evidence of such sinking.
The oceanic shelf to the 100-fathom line
widens rapidly to the northward, reaching
its greatest extent off the Gulf of Maine,
where it is approximately 400 miles wide.
The central floor of the Gulf of Maine
is an ancient river valley to which the river
systems, represented by those now existent,
contributed their drainage, to be emptied
into the prehistoric sea by a single channel
and mouth still traceable on the sea floor
at the edge of the continental shelf.
"SHELF" LADEN WITH SEAFOOD
Throughout this extensive and compara
tively shallow oceanic margin, well illumi
nated by the sun's rays, conditions are fa
vorable for an enormous development of
the marine plants on which sea animals
feed: namely, the microscopic diatoms,
one-celled algae, and the larger seaweeds.
Here numerous streams empty their
loads of silt, rich in nitrates, phosphates,
and other chemicals needed for plant food.
The strong tides rushing into the narrow
ing channel from the open sea keep the
water stirred with upwelling currents plen
tifully supplied with oxygen.
Hordes of small crustaceans, the cope
pods, feed upon this plant life. At certain